Impairments in the capacity for cognitive emotion regulation (ER) have been shown in Major Depressive Disorder (MDD). Investigations of cognitive ER tasks during fMRI have detected alterations in neural activity associated with cognitive ER in depressed compared to healthy adults. Despite these compelling findings, to date, there have been studies examining the neural correlates of cognitive ER in depressed versus healthy children. The proposed training and research plans are intended to provide the skill and experience necessary to become a developmental affective neuroscientist focused on addressing this critical gap in the literature. The specific hypothesis behind the proposed research is that neural circuits underlying cognitive ER may provide valid neurobehavioral markers of childhood MDD. Depressed children are expected to exhibit positive correlations between neural activity in ventral brain regions (e.g., the amygdala) thought to be responsible for appraising emotion stimuli, and neural activity in dorsal brain regions thought to underlie cognitive strategies for reappraising emotional experiences (e.g. prefrontal cortices [PFC]). Healthy children are expected to exhibit the inverse relationship. Using the same fMRI paradigm proposed in this application, initial preliminary findings appear to support this hypothesis. The feasibility of the research plan is enhanced by the availability of a large NIMH R01 study population of depressed and healthy children. Utilizing this sample, first a pilot study aimed at examining the construct validity of fMRI as a neurobiological assessment tool of children's cognitive ER is planned. The pilot study will provide opportunities to modify and optimize the fMRI task. Next, the cognitive ER task developed will be used to test the hypothesis about differences in neural circuitry in a larger sub-group of healthy and depressed children. The second aim is based on empirical evidence suggesting that dysfunctional neural activity in emotion processing and ER brain regions in adult samples are strongly correlated with impaired cognitive ER processes. Over 4 decades of cognitive-behavioral findings have implicated these same dysfunctional cognitive ER processes and subsequent maladaptive strategies (e.g., suppression and rumination) in the development and course of MDD. Thus, examining the neurodevelopmental substrates of cognitive ER during childhood may provide the opportunity to identify neurobehavioral markers of risk for and/or the diagnosis of MDD in childhood. Early identification of neurobehavioral markers may contribute to the advancement of novel preventive interventions aimed at minimizing the burden of MDD on the public health. To date, no study has used fMRI to examine the neural substrates of ER in healthy and depressed children. The unique mentorship and training opportunities available to the applicant would provide the necessary education and experience to launch a career as an independent scientist in the field of Translational Developmental Neuroscience. A future program of research examining the neurobehavioral underpinnings of abnormal ER development in mood-disordered children is planned.